-- Have you watched the latest TV program Running Man?
-- Of course! It's popular with __________ the young ________ the old.
在x轴的原点O和轴上的P点,分别固定同种电荷Q1和Q2,已知Q1<Q2,OP距离为2d,则场强为零的坐标x区间为( )
①若 ab <0,求a﹣b的值;
②若|a﹣b|=﹣(a﹣b),求a﹣b的值.